// read date from the serial and turn ON or OFF a light depending on the value

char val;             //Data received from the serial port
int ledPin = D8;        //Set the pin to digital I/O D8

void setup() {
  pinMode (ledPin, OUTPUT); //set pin as OUTPUT
 //Serial.swap(1);          //Use alternate pins for tx-rx
 Serial.begin(9600);        //Start serial communication at 9600 bps
}

void loop() {
  if (Serial.available()) {  //if data is available to read,
    val = Serial.read();     //read it and store it in val
  }
  if (val == 'H') {               //if H was received
    digitalWrite(ledPin, HIGH);   //turn the LED on
  } else {
    digitalWrite(ledPin, LOW);    //Otherwise turn it OFF
  }
  delay(100);                     //wait 100 milliseconds for next reading
}